AS2 Alien inland water species

Development

Invasive alien species

Altogether 25 alien species have been recorded from Finland's inland waters. These species have spread to natural water habitats thanks to human actions. Seven of these may be considered invasive and 12 potentially invasive. Six other alien species are not known to be invasive.

The number of alien inland water species has increased steadily thoughout the whole 20th century as well as the first decade of the 21st century. No similar peak during the past two decades can be seen as in the case of alien Baltic Sea species. As large a share as as two thirds of the species have been brought to Finland intentionally. Introductions of new species were done up to the 1970s after which this practice has been given up.

Clearly the greatest number of alien species has been recorded from the southwestern parts of the country. Here also natural species diversity is at its highest as is the magnitude of human actions, intentional and unintentional introductions included. Apart from northern Lapland, all other inland water regions host approximatley ten alien species each.

Brook Trout Salvelinus fontinalis

Signal GrayfishPacifastacus leniusculus

Reed MannagrasGlyceria maxima

American waterweedElodea canadensis

Grayfish Plague, As- and Ps1-types, Aphanomyces astaci (As, Ps1)

Potentially invasive alien species

a Crayfish* Orconectes limosus

Prussian Carp Carassius aurelius gibelio

Peled Coregonus peled

Common Carp Cyprinus carpio

Pink SalmonOncorhynchus gorbuscha

Rainbow TroutOnchorhynchus mykiss

Lake TroutSalvelinus namaycush

Round GobyNeogobius melanostomus

Danube GrayfishAstacus leptodactylus

Chinese Mitten CrabEriocheir sinensis

Amur Sleeper* Perccottus glenii

an Amphipoda* Gmelinoides fasciatus

Marmorkrebs* Procambarus sp.

Tropical HornworthCeratophyllum submersum

a waterweed* Elodea nuttalii

Fringed Water-lily* Nymphoides peltata

a parasitic nematode worm Anguillicola crassus

Other invasive alien species

Brown Bullhead Ameiurus nebulosus

Brook Stickleback Culaea inconstans

Moderlieschen Leucaspius delineatus

Marsh Frog Pelophylax ridibundus

Sweet Flag Acorus calamus

a peritrich ciliate Cothurnia variabilis

Prorocentrum minimum

This indicator will be checked in early 2011 after the national strategy on invasive alien species has been published.